Triggered Uplink Transmissions in Wireless Local Area Networks

1. A method for communicating in a wireless communication network, the method comprising: generating, at a first communication device, a trigger frame to trigger simultaneous uplink transmissions by multiple second communication devices, wherein the trigger frame includes a padding portion, and wherein a length of the padding portion is determined based on respective time duration requirements of the multiple second communication devices, the respective time duration requirements for preparing uplink transmission by the corresponding second communication devices; transmitting, with the first communication device, the trigger frame to the multiple second communication devices; and receiving, at the first communication device, the simultaneous uplink transmissions, triggered by the trigger frame, from the multiple second communication devices.

2. The method of claim 1 , wherein generating the trigger frame includes appending the padding portion after one or more information fields of a frame body portion of the trigger frame and before a frame check sequence (FCS) field of the trigger frame.

3. The method of claim 1 , further comprising, receiving, at the first communication device from the multiple second communication devices, the respective time duration requirements of the multiple second communication devices, and determining, with the first communication device, the length of the padding portion based on the received respective time duration requirements of the multiple second communication devices.

4. The method of claim 3 , wherein receiving the respective time duration requirements of the multiple second communication devices comprises receiving the respective time duration requirements during association with the corresponding second communication devices.

5. The method of claim 3 , wherein determining the length of the padding portion comprises determining the length of the padding portion based on a longest one of the time duration requirements received from the second communication devices.

6. The method of claim 1 , wherein determining the length of the padding portion comprises determining the length of the padding portion such that a sum of (i) a time duration of a predefined interframe space between an end of the trigger frame and a beginning of the uplink transmission triggered by the trigger frame and (ii) a time duration the padding portion is equal to or greater than a longest one of the time duration requirements.

7. The method of claim 4 , wherein the predetermined interframe space is a short interframe frame space (SIFS).

8. The method of claim 6 , wherein determining the length of the padding portion comprises determining the length of the padding portion such that a sum of (i) a time duration of a predefined interframe space between an end of the trigger frame and a beginning of the uplink transmission triggered by the trigger frame, (ii) a time duration of the padding portion and (iii) a time duration of one or more per-user information subfields in the trigger frame after a per-user information subfield corresponding to a second communication device having the longest one of the time duration requirements, and (iv) a frame check sequence (FCS) field in the trigger frame is equal to or greater than the longest one of the time duration requirements.

9. The method of claim 1 , wherein generating the trigger frame further comprises including, in the trigger frame, an indication of a beginning of the padding portion in the trigger frame.

10. The method of claim 1 , wherein the trigger frame is a control frame of a trigger subtype, and wherein generating the trigger frame further comprises including, in the trigger frame, an indication that the trigger frame is the control frame of the trigger subtype.

11. The method of claim 10 , wherein including, in the trigger frame, the indication that the trigger frame is the control frame of the trigger subtype comprises including the indication in an initial portion of a frame control field of the trigger frame such that the indication is entirely included in a first orthogonal frequency division (OFDM) symbol that includes the initial portion of the trigger frame.

12. The method of claim 1 , wherein receiving the simultaneous uplink transmissions from the multiple second communication devices comprises receiving an uplink orthogonal frequency division multiple access (OFDMA) from the multiple second communication devices, wherein the OFDMA transmission includes the simultaneous uplink transmissions, triggered by the trigger frame, in respective frequency channels allocated to respective ones of the multiple second communication devices.

13. A first communication device, comprising: a network interface device having one or more integrated circuits configured to generate a trigger frame to trigger simultaneous uplink transmissions by multiple second communication devices, wherein the trigger frame includes a padding portion, and wherein a length of the padding portion is determined based on respective time duration requirements of the multiple second communication devices, the respective time duration requirements for preparing uplink transmission by the corresponding second communication devices; transmit the trigger frame to the multiple second communication devices; and receive the simultaneous uplink transmissions, triggered by the trigger frame, from the multiple second communication devices.

14. The first communication device of claim 11 , wherein the one or more integrated circuits are configured to append the padding portion after one or more information fields of a frame body portion of the trigger frame and before a frame check sequence (FCS) field of the trigger frame.

15. The first communication device of claim 11 , wherein the one or more integrated circuits are further configured to receive, from the multiple second communication devices, the respective time duration requirements of the multiple second communication devices, and determine the length of the padding portion based on the received respective time duration requirements of the multiple second communication devices.

16. The first communication device of claim 15 , wherein the one or more integrated circuits are configured to determine the length of the padding portion such that a sum of (i) a time duration of a predefined interframe space between an end of the trigger frame and a beginning of the uplink transmission triggered by the trigger frame and (ii) a time duration the padding portion is equal to or greater than a longest one of the time duration requirements.

17. The first communication device of claim 16 , wherein the predetermined interframe space is a short interframe frame space (SIFS).

18. The first communication device of claim 15 , wherein the one or more integrated circuits are configured to receive the respective time duration requirements during association with the corresponding second communication devices.

19. The first communication device of claim 15 , wherein the one or more integrated circuits are configured to determine the length of the padding portion based on a longest one of the time duration requirements received from the second communication devices.

20. The first communication device of claim 19 , wherein the one or more integrated circuits are configured to determine the length of the padding portion such that a sum of (i) a time duration of a predefined interframe space between an end of the trigger frame and a beginning of the uplink transmission triggered by the trigger frame, (ii) a time duration of the padding portion and (iii) a time duration of one or more per-user information subfields in the trigger frame after a per-user information subfield corresponding to a second communication device having the longest one of the time duration requirements, and (iv) a frame check sequence (FCS) field in the trigger frame is equal to or greater than the longest one of the time duration requirements.

21. The first communication device of claim 13 , wherein the one or more integrated circuits are configured to generate in the trigger frame to include an indication of a beginning of the padding portion in the trigger frame.

22. The first communication device of claim 13 , wherein the trigger frame is a control frame of a trigger subtype, and wherein the one or more integrated circuits are configured to generate the trigger frame to include, in the trigger frame, an indication that the trigger frame is the control frame of the trigger subtype.

23. The first communication device of claim 22 , wherein the one or more integrated circuits are configured to include the indication in an initial portion of a frame control field of the trigger frame such that the indication is entirely included in a first OFDM symbol that includes the initial portion of the trigger frame.

24. The first communication device of claim 13 , wherein the one or more integrated circuits are configured to receive an uplink orthogonal frequency division multiple access (OFDMA) from the multiple second communication devices, wherein the OFDMA transmission includes the simultaneous uplink transmissions, triggered by the trigger frame, in respective frequency channels allocated to respective ones of the multiple second communication devices.